Pesticidal unsymmetrical bis-arylcarbamate sulfide compounds containing a 2,3, dehyrobenzofuran group

Abstract

Unsymmetrical bis-[N-alkyl-N-arylcarbamate] sulfide compounds exhibit outstanding miticidal, nematocidal and insecticidal activity, coupled with substantially reduced mammalian toxicity and phytotoxicity. SUMMARY OF THE INVENTION This invention relates to a novel class of unsymmetrical bis-arylcarbamate sulfide compounds and to methods of preparing them. This invention also relates to insecticidal, nematocidal and miticidal compositions comprising an acceptable carrier and an insecticidally or miticidally effective amount of a compound of this invention as well as to a method of controlling insects, mites and nematodes by subjecting them to an insecticidally, miticidally or nematocidally effective amount of a compound of this invention. The bis-carbamate compounds of this invention exhibit wide spectrum high level insecticidal activity as well as relatively low mammalian toxicity. This unique combination of high insecticidal activity and low mammalian toxicity permit the use of the novel unsymmetrical bis-carbamate compounds of this invention in relative safety. DESCRIPTION OF THE INVENTION This invention relates to compounds of the formula: ##STR1## wherein: R' and R" are the same or different and are alkyl having from 1 to 4 carbon atoms; R 1 and R 2 are individually hydrogen or alkyl having from 1 to 4 carbon atoms; R 3 is: (A) naphthyl, benzodioxolanyl, tetrahydronaphthyl, indanyl or benzothienyl, all of which may be either unsubstituted or substituted with one or more alkyl groups. (B.) phenyl either unsubstituted or substituted with one or more alkyl having from 1 to 12 carbon atoms, alkoxy, alkylthio, alkylsulfinyl, alkylsulfonyl, alkylthioalkyl, alkylsulfinylalkyl, alkylsulfonylalkyl, dialkylamino or nitro groups; With the proviso that R 3 may not include more than eight aliphatic carbon atoms, except as noted. Other compounds which are illustrative of the new compounds of this invention are: N-[2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate] N-[3-(1-methylpropyl)phenyl methylcarbamate] sulfide. N-[2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate] N-[(4-dimethylamino-3,5-xylylmethylcarbamate] sulfide. N-[2,3-dihydro-2-methyl-7-benzofuranylmethylcarbamate] N-[2-isopropoxyphenyl methylcarbamate] sulfide. N-[2,3-dihydro-2,2-dimethyl-7-benzofuranylmethylcarbamate] N-[4-benzothienyl methylcarbamate] sulfide. N-[2,3-dihydro-2,2-dimethyl-7-benzofuranylmethylcarbamate] N-[5,6,7,8-tetrahydronaphthyl methylcarbamate] sulfide. N-[2,3-dihydro-2,2-dimethyl-7-benzofuranylmethylcarbamate] N-[3,4,5-trimethylphenyl methylcarbamate] sulfide. N-[2,3-dihydro-2,2-dimethyl-7-benzofuranylmethylcarbamate] N-[4-methylthio-3,5-xylylmethylcarbamate] sulfide. N-[2,3-dihydro-2,2-dimethyl-7-benzofuranylmethylcarbamate] N-[4-dimethylamino-3-tolyl methylcarbamate] sulfide. N-[2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate] N-[4-indanylmethylcarbamate] sulfide. N-[2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate] N-[2-ethylthiomethylphenyl methylcarbamate] sulfide. N-[2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate] N-[2-ethylsulfinylmethylphenyl methylcarbamate] sulfide. N-[2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate] N-[4-methylsulfinyl-3,5-xylylmethylcarbamate] sulfide. N-[2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate] N-[3,5-diisopropylphenyl methylcarbamate] sulfide. N-[2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate] N-[2,2-dimethylbenzodioxolanyl-4-methylcarbamate] sulfide. All of the compounds within the purview of the generic formula set forth above exhibit miticidal and insecticidal activity to a lesser or greater extent. Accordingly, these compounds are extremely useful for the control of insect, nematode and mite pests. Some of these compounds exhibit very high levels of miticidal, nematocidal and insecticidal activity in extremely small dosages while others require larger dosages to be effective. In general, the compounds of this invention are either totally lacking in phytotoxicity or exhibit only minimal phytotoxicity with respect to economically important crop species. In addition, these compounds exhibit substantially reduced levels of mammalian toxicity as compared to known pesticidal compounds having a comparable spectrum of activity against insect, arachnid and nematode pests. Preferred because of their higher levels of miticidal and insecticidal activity are the compounds of this invention in which: R', r", r 1 and R 2 are methyl; R 3 is naphthyl, or phenyl substituted with one or more alkoxy, alkyl, alkylthio or dialkylamino groups. The unsymmetrical bis-[N-alkyl-N-arylcarbamate] sulfide compounds of this invention can be conveniently prepared by a variety of methods. One preferred method is illustrated by the reaction scheme set forth below in which R', R", R 1 , R 2 and R 3 are as described above, except as noted: ##STR2## METHOD I is a two-step reaction sequence which can be conducted either in-situ or the carbamate-sulfenyl carbamoyl halide intermediate (III) of Step A can be isolated and used as the reactant of Step B at some latter time. In Step A, one equivalent of an appropriately substituted hydroxyl reactant, either 2,2-dimethyl-2,3-dihydrobenzofuran-7-ol or R 3 OH is reacted with one equivalent of the bis-(N-alkyl-N-fluorocarbonylamino) sulfide reactant (II), in the presence of at least one equivalent of an acid acceptor, preferably in an aprotic solvent to yield the intermediate carbamate sulfenyl carbamoyl halide (III). In Step B, an equivalent of the intermediate carbamate sulfenyl carbamoyl halide (III) reactant is then reacted with second equivalent of a hydroxyl reactant, R 3 OH if 2,2-dimethyl-2,3-dihydrobenzofuran-7-ol was used as the hydroxyl reactant in step A or 2,2-dimethyl-2,3-dihydrobenzofuran-7-ol if R 3 OH was used as the hydroxyl reactant of Step A. Step B is also conducted in the presence of at least one equivalent of an appropriate acid acceptor and in an aprotic solvent, to yield the desired bis-arylcarbamate compound (V). The reactions of METHOD I is normally conducted in an aprotic organic solvent. Illustrative of aprotic organic solvents which are suitable as reaction solvents in the practice of the preferred embodiments of this invention are saturated and unsaturated aliphatic and aromatic hydrocarbons, e.g. hexane, cyclohexane, octane, dodecane, naphtha, decalin, kerosene, tetrahydronaphthalene, benzene, toluene, xylene, naphthalene, alkylnaphthalene, or the like, ethers such as tetrahydrofuran, tetrahydropyran, diethyl ether, dioxane, 1,2-dimethoxybenzene, 1,2-ethoxybenzene, the dialkyl ethers of ethylene glycol, of butylene glycol, or diethylene glycol, of dipropylene glycol, or chlorinated aliphatic hydrocarbons as for example, chloroform, dichloromethane, carbon tetrachloride or the like. The acid acceptor utilized in the conduct of the reaction of METHOD I may be either an organic or inorganic base. Illustrative of organic bases that are useful as acid acceptors are tertiary amines, alkali metal alkoxides or the like. Bases such as sodium hydroxide, potassium hydroxide or the like are illustrative of inorganic bases which are useful in the conduct of this reaction. Preferred acid acceptors are aromatic and aliphatic tertiary amines, such as triethylamine, pyridine, trimethylamine, 1,4-diazobicyclo [2.2.2] octane and the like. When an inorganic base is used as the acid acceptor, phase transfer agents may be used to facilitate the transfer of the acid acceptor across the organic/inorganic phase interface. Illustrative of useful phase transfer agents are crown ether compounds, quaternary ammonium halide compounds or the like. In these reactions, the reaction temperature is not critical and can be varied over a wide range. The reaction is preferably conducted at a temperature of from about -30° C. and upwards to approximately 130° C. Particularly preferred reaction temperatures are from about 0° C. to about 75° C. Reaction pressures are not critical. The process can be conducted at either subatmospheric, atmospheric or superatmospheric pressure. For convenience the reaction is usually conducted at atmospheric or autogeneous pressure. Hydroxylated aryl compounds employed as reactants in the reactions of METHOD I are well known compounds that can be prepared by well known synthetic procedures or obtained from commercial sources. The bis-(N-alkyl-N-fluorocarbonylamino) sulfide precursors can be conveniently prepared by reacting sulfur dichloride with N-alkylcarbamoyl fluoride in toluene in the presence of an acid acceptor as for example triethylamine or pyridine. This procedure is described in more detail in U.S. Pat. No. 3,639,471.

What is claimed is: 
     
       1. A compound of the formula: ##STR8## wherein: R' and R" are the same or different and are alkyl having from 1 to 4 carbon atoms; R 1  and R 2  are individually hydrogen or alkyl having from 1 to 4 carbon atoms;   R 3  is: (A) naphthyl, benzodioxolanyl, tetrahydronaphthyl, indanyl or benzothienyl, all of which may be either unsubstituted or substituted with one or more alkyl groups.   (B) phenyl either unsubstituted or substituted with one or more alkyl having from 1 to 12 carbon atoms, alkoxy, alkylthio, alkylsulfinyl, alkylsulfonyl, alkylthioalkyl, alkylsulfinylalkyl, alkylsulfonylalkyl, dialkylamino or nitro groups;     with the proviso that R 3  may not include more than eight aliphatic carbon atoms, except as noted.   
     
     
       2. A compound according to claim 1 wherein R' and R" are methyl. 
     
     
       3. A compound according to claim 1 wherein R 3  is naphthyl or substituted phenyl wherein the permissible substituents are one or more alkyl, alkoxy, alkylthio, nitro or dialkylamino. 
     
     
       4. N-[2,3-Dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate] N-[1-naphthyl methylcarbamate] sulfide. 
     
     
       5. N-[2,3-Dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate] N-[3-isopropylphenyl methylcarbamate] sulfide. 
     
     
       6. N-[2,3-Dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate] N-[4-tert-butylphenyl methylcarbamate] sulfide. 
     
     
       7. An insecticidal and nematocidal composition comprising an acceptable carrier and as the active toxicant an insecticidally or nematocidally effective amount of a compound according to claim 1. 
     
     
       8. An insecticidal and nematocidal composition comprising an acceptable carrier and as the active toxicant an insecticidally or nematocidally effective amount of a compound according to claim 2. 
     
     
       9. An insecticidal and nematocidal composition comprising an acceptable carrier and as the active toxicant an insecticidally or nematocidally effective amount of a compound according to claim 3. 
     
     
       10. An insecticidal and nematocidal composition comprising an acceptable carrier and as the active toxicant an insecticidally or nematocidally effective amount of a compound according to claim 4. 
     
     
       11. An insecticidal and nematocidal composition comprising an acceptable carrier and as the active toxicant an insecticidally or nematocidacidally effective amount of a compound according to claim 5. 
     
     
       12. An insecticidal and nematocidal composition comprising an acceptable carrier and as the active toxicant an insecticidally or nematocidally effective amount of a compound according to claim 6. 
     
     
       13. A method of controlling insects and nematodes which comprises subjecting them to an insecticidally or nematocidally effective amount of compound according to claim 1. 
     
     
       14. A method of controlling insects and nematodes which comprises subjecting them to an insecticidally or nematocidally effective amount of compound according to claim 2. 
     
     
       15. A method of controlling insects and nematodes which comprises subjecting them to an insecticidally or nematocidally effective amount of compound according to claim 3. 
     
     
       16. A method of controlling insects, and nematodes which comprises subjecting them to insecticidally or nematocidally effective amount of compound according to claim 4. 
     
     
       17. A method of controlling insects, and nematodes which comprises subjectin them to insecticidally, or nematocidally effective amount of compound according to claim 5. 
     
     
       18. A method of controlling insects, and nematodes which comprises subjecting them to insecticidally, or nematocidally effective amount of compound according to claim 6.